Which authentication framework is commonly used to enforce network access control on switches?

• A. 802.11i
• B. IPsec
• C. 802.1X
• D. TLS

Answer: (C)

Port-based network access control is what this concept tests on switches. 802.1X defines a framework where a switch acts as the authenticator and blocks the port until the connecting device (the supplicant) proves its identity to an authentication server, typically via RADIUS. The credentials flow uses EAP over LAN (EAPOL) on the local link, and once authentication succeeds, the port is opened and the device can be placed into a specific VLAN or given appropriate access controls. This is precisely how a switch enforces network access control at the edge. The other options address different security goals: 802.11i is for wireless encryption, IPsec provides IP-layer protection between endpoints, and TLS secures individual sessions rather than controlling access at the switch port. Hence, the framework that fits NAC on switches is 802.1X.